1. Field of the Invention
The present invention generally relates to a method for making a circuit board structure, the circuit board structure and a package structure obtained therefrom. In particular, the present invention is directed to a method for making a circuit board structure and a package structure by means of a carrier with an attached release film to support a copper film covered with a solder mask to the circuit board structure and the package structure.
2. Description of the Prior Art
A circuit board is an essential component of an electronic device. With the trend of always scaling down the size of the electronic devices, various carrier structures are therefore proposed to support the die. Some pins extend outwards to connect other circuits surrounding the circuit board to form proper electrical connections.
As far as the current technology is concerned, a circuit structure called “lead frame” is conventionally known. FIGS. 1-4 illustrate a method for making a traditional lead frame. Please refer to FIG. 1, first a metal substrate 101 is provided. Second, please refer to FIG. 2, the metal substrate 101 is patterned to form a circuit pattern 110 and a die pad 111 which correspond to a die (not shown). Later, via holes 122 are formed, pins 120 are connected to the metal substrate 101 as well as pins 120 and the die pad 111 are plated with silver 121. Next, please refer to FIG. 3, the die 130 is attached to the die pad 111 then followed by a wire bonding step and a tin plating step. Afterwards, please refer to FIG. 4, the pins are shaped to obtain a package structure 102. The data in the die is connected with the outer circuits by the pins 120.
However, as the data processed by the die increases and the speed for processing needs to be higher, the lead frame as illustrated cannot provide more pins 120 to meet the demands because the space around the die is so limited. In such a way, the application of the traditional lead frame 102 as a result is restricted.
FIG. 5 illustrates another carrier structure 201 for supporting dies. In the carrier structure 201, the circuit patterns 220 are respectively disposed on both opposite sides of the substrate 210. In addition, the solder mask layer 230 is selectively disposed on both opposite sides of the substrate 210 to properly protect the circuit pattern 220. Apart from this, some of the circuit pattern 220 is exposed. In the carrier structure 201, independent solder mask layers 231/232 need to be formed on both opposite sides of the substrate 210. The patterns of the solder mask layers 231/232 are usually distinctively different so that they can cope with different demands, such as location, of die pads (not shown) and different solder balls (not shown).
After the carrier structure 201 for supporting dies as illustrated in FIG. 5 undergoes suitable packaging steps, the package structure 202 as illustrated in FIG. 6 is obtained. In addition to the substrate 210, the circuit pattern 220, the solder mask layer 230, and the solder mask layers 231/232 as illustrated in FIG. 5, there are an extra die pad 220, die 240, bonding wire 250, sealant material 200 and solder balls 270 in the package structure 202 as illustrated in FIG. 6 due to the subsequent packaging steps.
The die 240 is disposed on the die pad 211 within the circuit pattern 220 and surrounded by the solder mask layer 231 at the same time as well as electrically connected to other parts of the circuit pattern 220 by means of the bonding wires 250. The sealant material 200 completely covers the die pad 211, the die 240, the bonding wire 250 and partially covers the substrate 210 and the solder mask layer 230. The solder balls 270 are surrounded by the solder mask layer 232. In both the carrier structure 201 for supporting dies as illustrated in FIG. 5 and the package structure 202 as illustrated in FIG. 6, the solder mask layers 231/232 are independently disposed on two opposite sides of the substrate 210 and extend to the margins of the substrate 210.
In the light of the above-mentioned carrier structures, the package structures and the conventional methods for making lead frames are not yet perfect, thus other novel carrier structures, package structures and the fabrication methods are still needed to provide a much simpler structure and to be free from conventional pin count restrictions.